An immense new crack has formed in Greenland’s Petermann glacier, and NASA scientists have now returned the first close-up images of the fissure, which may herald the birth of yet another massive iceberg from the glacier.
Petermann Glacier, located along the northern coast of Greenland, is one of the largest of the island nation’s glaciers that connects the Greenland ice sheet directly to the ocean. The leading end of the glacier, which floats atop water as an immense ice shelf, has already lost enough ice since 2010 to cover the island of Manhattan six times over. Up until 2010, this tongue of ice stretched over 70 kilometers from the ice shelf’s grounding line (the point where the ice is in direct contact with the island’s bedrock) to the leading edge.
On August 5, 2010, a 250 square kilometer ice island broke off from the end of the shelf, then floated out of the glacier’s fjord and into the waters of the Nares Strait, between Greenland and Canada’s Ellesmere Island. >/h1>
It’s area was roughly 4 times larger than the island of Manhattan, and it was considered the largest single chunk of ice lost from the Arctic since 1962. This shortened the ice shelf to just around 55 kilometers long.
— Stef Lhermitte (@StefLhermitte) April 12, 2017
A larger, older rift, which has been growing for at least the past two years, is visible in the distance. The new crack is near the bottom centre of the image, running from lower left towards middle-right.
According to an Operation Icebridge post on Facebook:
“The shaded feature near bottom center is a medial flowline, whose presence may exert a stagnating effect on the propagation of the new rift toward the older one.” This “medial flowline” is the larger feature that runs roughly perpendicular to the new crack.
The location of this new crack is raising some questions, because these kinds of fissures don’t usually form around the middle of the ice shelf. According to what Lhermitte posted on social media, it may have formed due to what’s known as ocean forcing – when the ice shelf is weakened by warm ocean water underneath it.
Simply by comparing the various leading edges, it’s clear that if this new crack is the start of a new calving event, the resulting ice island will be larger than the one that broke away in 2012, perhaps between 130 and 180 square kilometres.